1. Field of the Disclosure
The present disclosure generally relates to the design of ice making machine evaporator components and the joining process of the evaporator components. In particular, the present disclosure relates to the design and joining of ice making machine evaporator partitions having a crisscross pattern of partitions, and the joining of those partitions to an evaporator pan.
2. Discussion of the Background Art
Conventional ice making machines have an evaporator that is constructed using partitions assembled in a crisscross pattern (generally crisscrossed at about a 90° angle, hereinafter referred to as “horizontal” partitions and/or “vertical” partitions) and joined to an evaporator pan using only butt joints. The crisscross pattern forms individual vessels or cells where ice cubes are formed. On the side of the evaporator pan opposite the crisscross pattern of partitions is generally a serpentine refrigeration coil that chills the evaporator pan, providing an ice-forming surface on the crisscross side of the evaporator pan such that water cascading down the side having the partitions forming the cells will freeze and gradually build up within the cells, forming ice cubes. Once a sufficient amount of ice has formed in the cells, the ice cubes are harvested using a hot gas bypass circuit in the refrigeration system. During the harvest cycle in a conventional ice making machine, the hot gas warms the contact surface between the cubes and the evaporator pan and the cubes are released to fall into, e.g., a storage receptacle. Conventional ice making machine evaporators are constructed using a copper evaporator pan, copper partitions, and a copper serpentine tube or tubes.
The crisscross pattern of the partitions, as mentioned above, forms cells. These cells have four walls with an interior volume determined by the area (L×W) of the cell surface times the height/depth of the cell walls. The conventional design for the partitions forming the cells is to have a large aspect ratio (length or width to height, or L/W:H) with slots cut halfway across the height of each partition at locations where intersections between a horizontally disposed and a vertically disposed partition will form. As a result, the crossing (vertical and horizontal) partitions each make up slightly less than half the material height as they cross each other. The slots are of sufficient cross-sectional dimension to accommodate the width of the partition of the crossing partition that slides into it. However, the slot cross-sectional dimension is not so large that the crossing partition has “wobble” or “play” when inserted; this could result in problems concerning, e.g., the release of the ice slab/cubes during harvest and, due to the fact that water expands during freezing at certain temperatures, the deformation of the relative size of the cells by water freezing in the spacing provided by the “wobble” or “play”, resulting in damage to the crisscross assembly and/or non-uniform cube size. Thus, the slots generally provide relatively close or no clearance for the width of the mating partition. For partitions that are running horizontally on a vertically disposed evaporator pan in the ice making machine, the slots are cut in the height of the partition an angle 90° to the length of the partition. For the partitions that are running vertically on a vertically disposed evaporator pan in ice making machine, the slots are cut in the height of the partition at an angle, nominally 75°, to the length of the partition. The effect of the 75° angle in the vertically disposed partitions is to put an approximately 15° downward tilt into the horizontally running partitions that fit into the slots in the vertically running partitions. This 15° downward tilt allows gravity to pull the frozen ice slab/cubes from the evaporator pan cells during the harvest cycle of the ice making machine.
Conventional partitions also include what are known as “weep holes” for the purpose of allowing air to move around behind the slab of ice during the harvest cycle. Without the ability for air to move from cube cell to cube cell behind the slab of ice, the harvest cycle of the ice making machine would be impaired due to a vacuum that would be formed as the slab of ice is pulled away from the evaporator pan by gravity. These “weep holes” are intentionally located in the vertical partitions at the evaporator pan side of the vertical and horizontal partition intersections in conventional ice making machines so that a single “weep hole” is located at the corners of four ice cube-forming cells. Stated otherwise, the “weep hole” is located on the evaporator pan contact point at the end of a centerline running parallel to the angle of the slots in the vertically disposed partition. When the horizontal partitions are joined with the angled slots of the vertical partitions, the open end of the slot on the horizontal partition joins or mates with the “weep hole” located on the evaporator pan contact point at the end of the above-described center line parallel to the angle of the slots on the vertically disposed partition. The result is that there is a “void” (or combined weep hole/slot opening) at the intersection of the vertical and horizontal partitions adjacent the evaporator pan. This “void” creates an area where the crisscrossed vertical and horizontal partitions do not contact the evaporator pan (i.e., the “weep holes”).
The vertical and horizontal partitions are assembled together in a crisscross pattern and placed on the evaporator pan to form a grid that divides the ice cubes from each other. The evaporator pan is generally contoured so that the crisscross partition grid is disposed on a concave surface of the evaporator pan and the serpentine refrigeration/hot gas coil is disposed on a convex surface of the evaporator pan. This assembly (i.e., crisscross partition grid and concave surface of the evaporator pan) needs to be joined together and is usually joined during the manufacturing process, typically by soldering or brazing. The result of the joinder by soldering/brazing is that each partition (vertical and horizontal) in the grid is joined to the evaporator pan by many solder butt joints. The partitions are not joined to each other (being held together by the close or no clearance between the mated partitions), only to the evaporator pan surface. The serpentine refrigeration/hot gas coil is also typically soldered or brazed to the convex side of the evaporator pan.
Once the partitions and serpentine tubing are soldered or brazed to the evaporator pan, a coating is typically applied to the assembly to confer food grade safety and corrosion protection to it. This coating is typically a layer of nickel plating, generally either electrostatically or electroless, applied to the assembly. As mentioned above, the partition grid is generally assembled together with tight clearances between the slots and the width of the inserted partition to ensure that the partitions remain parallel to each other. Because of the tight or no clearance and potential lack of clearance between the partition surfaces at their intersections, the plating solutions do not always penetrate into the vertical and horizontal partition intersections and provide plating to all the surfaces forming the partition intersections. The reason for this is that the “void” (i.e., “weep hole”) prevents capillary action from allowing the brazing or soldering alloy to wick into the tight clearance between the slot and the width of its mating partition. Without complete penetration, material forming the base materials of the evaporator pan and/or vertical and horizontal partitions may be left exposed.